Core/Spells: use SpellInfo class to get spell rank instead of SpellMgr helpers

src/server/scripts/Spells/spell_dk.cpp

@@ -953,11 +953,15 @@ class spell_dk_will_of_the_necropolis : public SpellScriptLoader
 
             bool Validate(SpellInfo const* spellInfo) OVERRIDE
             {
-                // can't use other spell than will of the necropolis due to spell_ranks dependency
-                if (sSpellMgr->GetFirstSpellInChain(SPELL_DK_WILL_OF_THE_NECROPOLIS_AURA_R1) != sSpellMgr->GetFirstSpellInChain(spellInfo->Id))
+                SpellInfo const* firstRankSpellInfo = sSpellMgr->GetSpellInfo(SPELL_DK_WILL_OF_THE_NECROPOLIS_AURA_R1);
+                if (!firstRankSpellInfo)
                     return false;
 
-                uint8 rank = sSpellMgr->GetSpellRank(spellInfo->Id);
+                // can't use other spell than will of the necropolis due to spell_ranks dependency
+                if (!spellInfo->IsRankOf(firstRankSpellInfo))
+                    return false;
+
+                uint8 rank = spellInfo->GetRank();
                 if (!sSpellMgr->GetSpellWithRank(SPELL_DK_WILL_OF_THE_NECROPOLIS_TALENT_R1, rank, true))
                     return false;
 
@@ -981,7 +985,7 @@ class spell_dk_will_of_the_necropolis : public SpellScriptLoader
             void Absorb(AuraEffect* /*aurEff*/, DamageInfo & dmgInfo, uint32 & absorbAmount)
             {
                 // min pct of hp is stored in effect 0 of talent spell
-                uint32 rank = sSpellMgr->GetSpellRank(GetSpellInfo()->Id);
+                uint8 rank = GetSpellInfo()->GetRank();
                 SpellInfo const* talentProto = sSpellMgr->GetSpellInfo(sSpellMgr->GetSpellWithRank(SPELL_DK_WILL_OF_THE_NECROPOLIS_TALENT_R1, rank));
 
                 int32 remainingHp = int32(GetTarget()->GetHealth() - dmgInfo.GetDamage());